When using flexible endoscopes in medical endoscopy one or a plurality of working channel(s) is limited by a tube or sheet made of plastic. One such channel is used for visually inspecting a target area and/or the path the endoscope takes inside a body. Other working channels might be used for delivering a transparent fluid for rinsing the target area of the endoscope, in particular the target area of a minimal invasive surgical operation. Furthermore, it is possible to use the working channels for introducing additional instruments, in particular instruments used for surgery. Such instruments include micropliers, guiding wires, small baskets for recovery of particles or material from the target area, e.g. smashed or wrecked urinary stones, as well as light transmitting fibers, in particular fibers transmitting the light emitted by a laser. It is one drawback of the known endoscopes that the flexibility of an endoscope might be reduced in an operational state by an instrument extending at least partially through the working channel. In order to avoid problems caused by such reduced flexibility the endoscopes are commonly introduced in a body without an instrument extending through the working channel. Subsequent to introducing the empty endoscope into the body the instruments are introduced into the working channel. Also from other reasons it might be necessary to introduce instruments into the working channels of an endoscope after inserting the endoscope inside a body. On example is a visual investigation of the lower calyces renales by a flexible ureterorenoscope in order to locate nephroliths and for subsequent fragmentation of the nephroliths and/or removal of the nephroliths. In such procedure it is helpful for the purpose of detecting the nephroliths to maintain an unlimited flexibility of the flexible ureterorenoscope using the whole lumen of the working channel for rinsing the optical target area. This means that an instrument used for subsequent fragmentation or retrieval of the nephroliths should not be introduced into the working channel of the ureteror-endoscope when trying to detect the nephroliths. It is preferred to use energy supplied by a laser and transmitted or delivered by a fiber for the fragmentation of nephroliths or urinary calculus. Such fiber usually comprises a distal end cut perpendicular to its optical axis in order to provide optimal contact of the blunt distal end with the urinary calculus that is to be fragmented. In spite of the used fibers being designed to reduce the flexibility of the endoscope as little as possible, introduction of the fibers into the working channel of a flexible endoscope still involves problems. Due to a remaining small stiffness of the fiber, in particular a glass fiber, a sharp end of the distal end of the fiber scratches or cuts the wall that limits the working channel. Such undesired effect causes damages of the surface of the inner wall of the endoscope or the fiber. The damages in particular occur in curved portions of the working channel. For a long term use, such effect might cause failure of the endoscope. In practice, up to every second maintenance work for flexible endoscopes is due to damages of the working channel caused by an introduction of an instrument or a fiber into the working channel. Each of such maintenance works might cause costs of more than US $1,000.
Whereas the present invention relates to endoscopes for multiple use with at least one lumen used for transmitting an optical signal to the physician, US 2003/0236517 A1 relates to a medical device for treatment of blood vessels using an introducer catheter for applying endovascular laser therapy. Usually, such introducer catheters are designed for single use due to the low costs of such catheter involving less costs for using a new catheter for the next body to be treated than disinfecting a used catheter. Such single use catheter comprises a protective sleeve with a single lumen with the optical fiber positioned therein. When moving the fiber through the working channel of the catheter, the distal end of the fiber is located inside the flexible sleeve such that a distal end of the flexible sleeve covers the edges built by the distal end of the fiber. In such manner, any damages of the limiting wall of the working channel are avoided. For a treatment of a saphenous vein, a small gauge needle is used to puncture the skin and access the vein. A guide wire is advanced into the vein through the lumen of the needle. The needle is then removed leaving the guide wire in place. A hemostasis introducer sheet is introduced into the vein over the guide wire and advance to 1 to 2 cm below the sapheno-femoral junction. A valve gasket provides a leak-proof seal to prevent a backflow of blood out of the sheet's proximal opening while simultaneously allowing the introduction of the fiber into the sheet. The valve gasket is made of elastomeric material such as rubber or latex. The gasket opens to allow insertion of the optical fiber and then seals around the protective sleeve containing the optical fiber. When inserting the optical fiber into the vein, the distal end of the fiber is protected by the protective sleeve. The distal end of the fiber embedded in the protective sleeve is inserted into the hemostasis sheet and advanced forward through the sheet lumen. As the protected fiber assembly is advanced through the curved pathway of the sheet shaft, the non-traumatic sleeve tip rather than the sharp edge of the optical fiber comes in contact with the inner sheet wall. Advantageously, the sleeve tip does not damage the inner wall of sheet shaft as it is advanced because of the sleeve's flexible material characteristics as well as because of its tapered or radiuses, non-traumatic distal profile. Moreover, the device eliminates the shavings of material of the working channel that may be cut away from the inner wall of the sheet shaft as an unprotected fiber tip is advanced. Accordingly, there is no risk of shaft material being deposited within the venous system or becoming adhered to the flat face of the optical fiber when the protective fiber assembly is used for transmitting laser energy. The fiber and the protective sleeve are advanced through the working channel until a connecting element comes in contact with a handle of the catheter. Once fully assembled the handle restricts relative movement of the protective sleeve with respect to the fiber as well as the working channel to a small range. Such range comprises a first limiting position correlating with an operational state wherein the distal end of the optical fiber is located inside the flexible sleeve. A second limiting position correlates with another operational state wherein the distal end of the optical fiber protrudes from the distal end of the protective sleeve. Once the physician has confirmed that the tip of the optical fiber is correctly positioned approximately 1 to 2 cm below the saphenous-femoral junction the device is placed in an operating position with the distal end of the fiber located outside the sleeve. The distal end of the fiber is exposed by retracting the connecting distal handle component while holding the proximal handle component stationary. The device is then in operating position, ready to delivery of laser energy to the diseased vein. After such treatment of the target area by the energy of a laser the catheter is then slowly withdrawn through the vein, preferably at a rate of 1-3 mm per second.
Further prior art is known from U.S. Pat. No. 2,571,653, U.S. Pat. No. 3,809,072 and U.S. Pat. No. 4,886,049.